Hi @Scottmoose, Yes I can tell already that it will be a matter of reducing excess gain. In the hobby room I had way too much gain at 125Hz and 200Hz, with a big null between them, at 162Hz. The sound was both boxy and boomy, as you can imagine. The 200Hz peak is particularly grating.
Regarding tweaking the damping, I have seen you recommend adding damping in the throats, but also in an older post (related to Silbury, IIRC) I saw you recommending stuffing the final sections of the horn (near the mouths).
In an effort to reduce the number of times I remove and re-install the driver screws, can you recommend a sane starting point? Perhaps better to wait till I run some sweeps and see what I am dealing with in-room.
Regarding tweaking the damping, I have seen you recommend adding damping in the throats, but also in an older post (related to Silbury, IIRC) I saw you recommending stuffing the final sections of the horn (near the mouths).
In an effort to reduce the number of times I remove and re-install the driver screws, can you recommend a sane starting point? Perhaps better to wait till I run some sweeps and see what I am dealing with in-room.
Okay, so I have the speakers set up in the listening room.
I have run some sweeps. These were done in HouseCurve with a calibrated UMIK-1 and the calibration file loaded. 4 sweeps from different room positions, averaged. As you can see, there is generally too much gain between ~90Hz and ~300Hz, with a really big room null at 257Hz. I am not concerned at all with the rest of the response. Note: the yellow line is the target curve, which is a modified Harman curve that I find particularly pleasing.
This tool makes it trivial to calculate an FIR filter to dump into CamillaDSP and fix all this, but I would much rather use damping to do the heavy lifting and then perhaps fine-tune it with software later.
I have run some sweeps. These were done in HouseCurve with a calibrated UMIK-1 and the calibration file loaded. 4 sweeps from different room positions, averaged. As you can see, there is generally too much gain between ~90Hz and ~300Hz, with a really big room null at 257Hz. I am not concerned at all with the rest of the response. Note: the yellow line is the target curve, which is a modified Harman curve that I find particularly pleasing.
This tool makes it trivial to calculate an FIR filter to dump into CamillaDSP and fix all this, but I would much rather use damping to do the heavy lifting and then perhaps fine-tune it with software later.
Thanks for the feedback. Part of the final plan is to install outriggers (for stability) and put felt feet on them.
Are you sure? I mean per Scott the 'hand off' is ~ 230 Hz due to floor loading/speaker depth and the T/S math I alluded to is the driver's upper mass corner where T/S box theory peters out at ~ (2*Fs/Qts) = ~ 248 Hz in free space before factoring in any series resistance that will lower it + whatever the driver/floor reflection is, so thinking maybe just a minor one and/or driver/ceiling and/or driver/side wall reflections.......
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As you’ve got them close to two room boundaries, I’d try moving them out from the rear wall by incremental steps of about 2” at a time - you might well tame those ripples. Much harder to fill the dip of a deep room mode.
As for outriggers and feet, I gotta assume you’d be DIYing those, so some solid 3/4”x 3”or so hardwood extending at least 4” either side and felt or Teflon appliance slider pads would be worth a look.
Of course you could get spendy an do 6mm aluminium bar and drill/tap for threaded cones, but I always found the careful alignment of the dimpled cups when using on bare flooring like in your photo was a royal pain.
As for outriggers and feet, I gotta assume you’d be DIYing those, so some solid 3/4”x 3”or so hardwood extending at least 4” either side and felt or Teflon appliance slider pads would be worth a look.
Of course you could get spendy an do 6mm aluminium bar and drill/tap for threaded cones, but I always found the careful alignment of the dimpled cups when using on bare flooring like in your photo was a royal pain.
I realize this is too late because OP has the sand thing going already, but I used lead shot back when lead wouldn't cause cancer and reproductive harm and was simply a soft metal that killed Roman wine drinkers. Also, the common metal was cheap at $10 a 25lb bag. Now you can use Teflon coated steel, or better use bismuth and tin alloy for a heavy non-resonant cavity. I read that the small bb shapes and granular sand help suppress the sound vibrations by creating heat. I don't know about that, I think it's mostly a mass thing. My current surround system has tweeters in lead filled chambers. I think it makes a difference but I have no data, sorry.
I do like the stiff foam idea, light and non-resonant, it works well in rockets. You could simply pack the chamber with damping, fill it with wool felt. I also think that several layers of differing damping materials will work better as a broadband damper.
The thing is, all of these crazy ideas will 'work' to some degree.
I’d rather not move them out from the wall if I can solve the problems any other way. I did choose these partially because they are designed to do well close to boundaries. I don’t want a speaker in front of the sliding door on the left.
Re: outriggers, thanks for the ideas! I bought some stainless steel bar with holes pre-drilled and might use that. It was cheap, but I am questioning the aesthetics. We’ll see.
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Glad to say I’ve had some success with some cheap, 3-layer kitchen sponges inserted carefully in the throats. Had to try three times, adding larger pieces each time. This is where things sit now. Still not perfect, but it tests much better and sounds pretty good at this point. As you can see, my assumed room null issue seems to have been reduced as well. Still, room for improvement.
For easier visual comparison, here is the initial test:
The sponge:
Dog like reggae:
For easier visual comparison, here is the initial test:
The sponge:
Dog like reggae:
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It’s been far too long since I’ve had a good listening session!
+1 Thought I had a pic of these with outriggers where I used some more of the petrified lumber to 'frame' its base perimeter such that it has (had? no clue who has them now) two front/back legs with a wide parallel bar across the front, so 4 adjustable feet after the owner (a truly life long functioning alcoholic) bumped into one, knocking both it and him over with both suffering some injuries.
Sheesh! Forgot to mention they were originally a tripod with a foot under the cab, but with the outriggers behind plus some added weight attached (concrete block) proved to be stable enough when bumped/stumbled into.
No, due to him having been a cowboy 'rangy' 6'4" (I'm ~5'9" at the time).
No, due to him having been a cowboy 'rangy' 6'4" (I'm ~5'9" at the time).
Damping in the chamber & throat area is the default; you can start to trim excess LF output by adding material above / below the deflectors, as relevant.
Damping material is always most effective at the point of maximum air velocity, which for LF frequencies is near the bifurcated physical termini; you can add some to the deflector surfaces also of course if pets etc. can't access them. And then it's literally a case of adjusting to suit your preferred balance -preferably per channel since few spaces are acoustically speaking completely symmetrical, although the one shown is probably more so than some.
The gain BW you measured is roughly in line with expected, near-raw, albeit with the usual variations you'd expect for room acoustics, mic. type & placement. So it appears to be behaving as intended, which is always a good start. 😉 As an advance suggestion -go easy with the Harman house curve on a direct-radiating wideband. I like it as a basis myself, especially for direct-radiating multiways, but (but) you can end up chasing your tail a bit with any nominal system response curve since it's not ideally accounting for differences in the actual polar / power responses in radically different systems. That's why, say, the so-called 'smiley face' curve with roughly symmetrical peaking LF and HF can actually sound quite balanced for many people since the one tends to cancel the others out. In the case of wideband drivers, with their reduced HF dispersion, tilting it down significantly can sometimes end up causing more of an LF heavy balance than in other setups -especially if you have a large (in relative terms) horn coupling to the room over a wide (again in relative terms) LF BW compared to a sealed or regular vented box.
That hound looks like I feel.
A BLH is just a big vent reflex alignment, so critically damping them is the 'easy peasy' way to dial them in.
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Hey, VW Beetles don't leak oil. They're just marking their spot. 🤣.......or under all pre '68 USA and all but one brand/model of UK/European vehicles I've kept more than a few hours.
Didn't Bill Woods have that VW bug with a big tractrix horn strapped to the roof?
Of course! Which artist/album were you playing?
I used to go to reggae sound system dances. I think perhaps my early experiences with those big bass scoops made me interested in back loaded horns.
